The proposed research deals with changes in nuclear protein composition and metabolism during tumorigenesis in the colonic epithelium. Two classes of chromosomal proteins (TNP1 and TNP2) are selectively synthesized soon after exposure to the carcinogen, 1,2-dimethylhydrazine. One of these, TNP1, has been identified as a DNA-binding fraction which appears to be localized on the transcriptionally-active genes in the dividing cell population of the tumor. The characteristic protein peaks which accumulate in colonic adenocarcinoma nuclei are not evident in normal embryonic or adult colonic epithelium. Similar proteins occur in human colonic adenocarcinomas, and they begin to appear in the nuclei of cells immediately surrounding the tumor. They are not evident in non-malignant intestinal neoplasms. Our aim is to pruify the major tumor-specific proteins from human adenocarcinoma nuclei. Antibodies to these proteins will be employed in immunofluorescence assays for their detection in single cells - to permit early diagnosis of malignant transformation in individuals at high risk for colon cancer. Related projects deal with methods for the purification and characterization of nuclear proteins using DNA-affinity chromatography and 2-dimensional gel electrophoresis. Methods for the quantitation of protein distributions in 2D gels by raster-scanning microdensitometry have been developed and are being applied to the DNA-binding proteins of colonic tumor nuclei.